Heating system

ABSTRACT

A water heating system uses a heated fluid storage tank to deliver a continuous supply of water heated to a desired temperature, such as between 100°-130° F. The system also includes a furnace with altitude-sensitive control circuitry to provide multiple sources of heat for the heating system in the most effective way given the altitude at which the system is located. The system also includes a micro-controller that adjusts certain system components in response to changes in atmospheric pressure conditions that are measured by an atmospheric-pressure sensor component: There is also an automatic-air-bleeder subsystem with an optical or ultrasonic sensor mounted adjacent a suitable air accumulator. Also included is an air-release solenoid and a fuel return line.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/421,365, filed Apr. 22, 2003 entitled “HeatingSystem”, and incorporated herein by reference. This application alsoclaims priority to U.S. Provisional Patent Application Serial No.60/380,586, filed May 14, 2002 and entitled “Heating System”.

FIELD OF THE INVENTION

[0002] The present invention relates generally to heating systems, andmore specifically, to a hydronic heating system and method forrecreational-vehicle (RV), marine and home heating applications thatincludes a system for altitude compensation for diesel-fire heaters, andan automatic air bleeder for removing unwanted air bubbles from heaterfuel.

BACKGROUND OF THE INVENTION

[0003] Heating systems for campers and recreational vehicles are widelyknown. Conventional water heating systems for recreational vehiclesgenerally fall into two classes. The first class includes systems thathave a heating element(s) that extends into a cavity that holds severalgallons of water. The heating element ultimately heats the entire volumeof water in the cavity. Drawbacks to this first class include a lack ofcontinuous hot water. In addition, the first class of systems takes arelatively long period of time to heat water. The second class involvessystems that heat a relatively small volume of water with a gas orelectric heating device. Conventional systems of the second classinclude propane, or other open flame “flash furnace” heating systemsthat directly heat domestic water supplied to the system. Open-flamesystems like these are relatively expensive and relatively unsafe whenused in a recreation vehicle. In addition, a propane system isineffective to provide a constant supply of hot water.

[0004] For heating devices used in the above heating systems, there arecertain problems caused when changes in atmospheric pressure (due tochanges in altitude or weather) undesirably affects heating-fuelcombustion. Conventional heating devices (heaters) are not constructedto change the combustion parameters, and as a result they do not performoptimally when such changes occur. The result is that heater exhaustemissions increase causing smoke, and giving off undesirablesmells/odors. Carbon also accumulates on the heater-burner tube andother system components. Overall, conventional heaterperformance/efficiency becomes low, maintenance becomes expensive, andultimately the heater becomes damaged.

[0005] Accordingly, for applications where the heater is used indifferent atmospheric pressure conditions, there is a need for theheater to be constructed to adjust combustion parameters based uponchanges in atmospheric pressure to maintain low exhaust emissions (e.g.Recreational Vehicle (RV) and household applications), maintain optimalperformance, and reduce the risk of heater damage or need formaintenance.

[0006] Generally, conventional diesel-fired heaters can characterized ashigh-pressure and low-pressure, where the pressure (high or low) refersto the pressure between the fuel pump and the fuel-atomizing deviceassociated with the heater. In connection with low-pressure diesel-firedheaters for RV, there have been conventional proposals to deal with thesituation where the RV (and heater) increase altitude by using aso-called zero-pressure regulator and a Venturi fuel-atomizing system toreduce the amount of fuel which is burned in the combustion process athigher altitude. One drawback to this method is that heatoutput/efficiency drops with each incremental increase in altitude at anapproximate rate of 5% for every 3000 ft.

[0007] Another problem associated with conventional diesel-fired heatersis that the associated fuel pump supplies fuel that is mixed withundesirable air bubbles. Passing through the fuel-atomizing component ofconventional systems, these air bubbles cause gaps in the fuel supplywhich can cause heater de-activation (so-called “flame out” conditions).When the heater flames out, a white cloud of smoke is generated becauseconventional control circuitry cannot immediately stop the fuel-deliverysubsystem. As a result, fuel is sprayed into a hot combustion chamberfor a period of time. This situation causes the smoke, or in the worstcase where the fuel re-ignites, explosions.

[0008] Objects of the invention include solving the problems associatedwith changes in atmospheric conditions, and those associated with airbubbles in the heater fuel.

SUMMARY OF THE INVENTION

[0009] The present invention overcomes the drawbacks of conventionalsystems by providing a water heating system that uses a heated fluidstorage tank to deliver a continuous supply of water heated to a desiredtemperature, such as between 100-130° F. The system also may combine aheated fluid storage tank with an altitude sensitive burner type furnaceto provide multiple sources of heat for the heating system.

[0010] To achieve the desired altitude compensation capability, thesystem includes a controller (preferably a micro-controller) thatadjusts certain system components in response to changes in atmosphericpressure conditions that are measured by an atmospheric-pressure sensorcomponent of the invention. For example, for low-pressure-typediesel-fired heaters, the invention is constructed to increase theamount of combustion air in response to a sensed increase in altitude.By increasing the pressure of the compressed air so that changes inaltitude will not affect the quantity of fuel absorbed through theheater nozzle (under Venturi effect), the altitude-compensationcontroller (or circuit) of the invention will adjust the amount of thecombustion air by controlling the sped of the combustion fan or thesurface (size) of the combustion-air-intake opening. This controller andmethod maintains a constant heat output regardless of changes inatmospheric pressure such as changes in altitude or weather.

[0011] The automatic air bleeder of the invention includes a suitablesensor (such as an optical or ultrasonic one) mounted adjacent asuitable air accumulator (for optical sensors, substantially transparentor clear glass, or a plastic tube are suitable; for ultrasonic sensors,plastic or rubber tubes are suitable). Also included is an air-releasesolenoid and a fuel return line.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIGS. 1 is a schematic diagram of a heating system according toone embodiment of the present invention.

[0013]FIG. 2 is a schematic diagram of an altimeter connected to themotor of a fan usable in the heating system of the invention.

[0014]FIG. 3 is a schematic diagram of an altimeter with a flashmicro-controller of the invention.

[0015]FIG. 4 is a schematic diagram of an automatic air-bleeder featureof the invention.

[0016]FIG. 5 is a schematic diagram showing a heater feature of theinvention for use in applications for low-pressure-type heaters and thatshows altitude compensation via fan-speed control.

[0017]FIG. 6 is a schematic diagram showing a heater feature of theinvention for use in applications for low-pressure-type heaters and thatshows altitude compensation via control of the combustion-air-intakesurface.

[0018]FIG. 7 is a schematic diagram showing a heater feature of theinvention for use in applications for high-pressure-type heaters andthat shows altitude compensation via controlling the flow of fuel fromthe fuel pump.

[0019]FIG. 8 is a schematic diagram showing a heater feature of theinvention for use in applications for high-pressure-type heaters andthat shows altitude compensation via control of thecombustion-air-intake surface.

[0020]FIG. 9 is a schematic diagram showing a heater feature of theinvention for use in applications for high-pressure-type heaters andthat shows altitude compensation via fan-speed control.

DETAILED DESCRIPTION AND BEST MODE OF THE INVENTION

[0021] A heating system according to one embodiment of the presentinvention is shown at 10 in FIG. 1. The heating system may be used toprovide a continuous supply potable hot water, and to provide heat to acoach or recreational vehicle. Additionally, the heating system may beused to warm the engine block of a coach in cold weather climates tomake the engine easier to start.

[0022] Heating system 10 uses a main heating fluid circuit 12 to provideheat for the potable hot water system, the coach heater system, and towarm the coach engine block in cold climates. A main circuit pump 13circulates heating fluid through circuit 12. The main heating fluidcircuit 12 includes a heater/boiler 14 configured to heat a volume ofheating fluid. Typically, the heater/boiler is configured to heat aheating fluid such as glycol; however, a mixture of glycol and water orother suitable high-heat-capacity liquid may be used as a heating fluid.

[0023] Still referring to FIG. 1, a diesel-fired burner 15 may heatheater boiler 14. A variable speed fan may provide burner 15 with airfor combustion of diesel fuel. The variable speed fan may be connectedto an atmospheric pressure sensor, as shown at 16 in FIG. 2. Atmosphericsensor 16 produces an electronic signal based on the externalatmospheric pressure. The electronic signal is amplified at amplifier 18and the signal is then processed in a signal-conditioning circuit 20.Additional signal conditioning may be applied at 22 in the form of aPWM, DC-DC converter, voltage regulator, or frequency inverter. Finallythe signal is sent to a variable-speed motor 24. Variable-speed motor 24drives a fan, as shown in FIGS. 5-9, that supplies air for combustion todiesel-fired burner 15. As the atmospheric pressure sensor senses lowerambient air pressure it may increase the speed of variable-speed motor24. Increasing the speed of the motor increases the amount of air blownin to the combustion chamber of the burner. The atmospheric pressuresensor may continuously vary the speed of the fan in response to changesin the atmospheric pressure.

[0024] Alternatively, the atmospheric pressure sensor may speed up thefan to increase the flow of air to the burner at discrete altitudeswhere ambient air pressure drops below specific thresholds. For example,from sea level to 2000 ft. the fan speed may be low. Above 2000 ft. upto around 6000 ft. the fan speed may be medium or higher than the lowsetting. Above 6000 ft. the fan speed may be high to compensate for thelower density of air at that altitude.

[0025] Referring again to FIG. 1, main heating fluid circuit 12 furtherincludes a heated expansion tank 26. Tank 26 may be heated by electricheating elements 28. A suitable heated expansion tank 26 is availablecommercially under the trade name COMFORTHOT™ Typically, heatingelements 16 are 2-kilowatt electric heating elements; however, anysuitable heating element may be used. Heating elements 28 are insertedinto tank 26 in a manner similar to a conventional residential electrichot water heater. Heat energy is stored in the tank 26, so in a sensetank 26 acts as a heat battery for the heating system capable ofproviding instant heat energy to any system that requires it. Theelectric elements maintain the heating fluid at an elevated temperaturewithout a large energy demand, while there is little or no demand forheat from the system. As demand for heat increases burner 15 of tank 26is activated and thus provides additional heat energy for heating waterultimately for use as shower water or as heating fluid that is used toheat the vehicle cabin or engine block.

[0026] Main heating fluid circuit 12 also includes a domestic water heatexchanger 32. Heating fluid in the main heating circuit flows throughdomestic water heat exchanger 32 to heat water. Water in the domesticwater system is heated by transferring heat from the heating fluid todomestic water in heat exchanger 32.

[0027] Domestic water system 34 supplies cold water to heat exchanger 32for heating. The heated water exits heat exchanger 32 and flows to amixing valve 36 that prevents hot water from exceeding a certaintemperature by mixing hot water from heat exchanger 32 with cold waterfrom the domestic water system.

[0028] Still referring to FIG. 1, heating system 10 includes anengine-hookup loop 38, an engine-hookup-loop pump 40 and an engine-heatexchanger 42. Main heating fluid circuit 12 flows through one side ofengine-heat exchanger 42. The engine-hookup loop and engine-heatexchanger may be used to extract excess heat from the engine of thecoach while it is operating. Opening engine-hookup loop 38 suppliesengine coolant to one side of heat exchanger 42. Heat exchanger 42transfers engine heat to the heating fluid in main heating fluid circuit12. Extracting heat energy from the coach's engine reduces the energydemands of the heating system.

[0029] Another benefit of engine-hookup loop 38 is that the heatingsystem may be used to warm the engine block of the coach prior tostarting the engine in cold climates. By pumping engine coolant throughengine-heat exchanger 42 at the same time the heating fluid iscirculating in circuit 12, heat is provided to the engine of therecreational vehicle. Preheating an engine block in cold climates makesit easier to start and reduces wear and tear on the engine.

[0030] A cabin-heating loop 44 may by attached to main-heating-fluidcircuit 12 that supplies heating fluid to heating fans (not shown) inthe cabin of the vehicle to provide the cabin of the vehicle with heat.A cabin-loop solenoid 46 opens and closes the cabin loop to selectivelyprovide the cabin with heat. Fluid pump 13 provides the pressure tocirculate heating fluid through the cabin-heating loop when the cabinloop solenoid is open. Each heating fan acts as a heat exchanger to warmair in the cabin.

[0031] Referring to FIG. 4, an air bleeder subsystem is shown that isconnectable within the fuel line that draws fuel for the diesel-firedheater (burner)(see FIGS. 5-9 below the fuel regulator and between thefuel pump and the fuel atomizing system). The air bleeder subsystemincludes any suitable sensor, such as an optical air/air-bubble detectoror ultrasonic sensor configured to detect a bubble in the fuel line.When a bubble is detected an air release solenoid opens the return lineto bleed air back to the tank or out a vent. The bubble detector thendetects that the bubble is no longer present and the solenoid closes thereturn line. The air bleeder enables the burner to run safely. Large airbubbles can extinguish the burner flame causing clouds of white smoke,exhaust emissions, carbon built-up and increase the cost of maintenance.In addition, re-igniting the burner flame repeatedly can damage theburner and cause premature wear.

[0032] Referring to FIGS. 5-6, the heating system of the invention isshown including the micro-controller (FIG. 3). The heating system may bethought of as a heat-management system designed to optimize threesources of heat. Heat may be generated from a vehicle engine, a dieselfurnace associated with a vehicle, or an electric-heating element. Heatis stored in heating fluid and used either to heat water (to be used byvehicle users for showering/washing) or to heat desired areas of thevehicle by directing the heating fluid through associated pipes. Acontrol board is used to control delivery of heat and other decisionsabout the heat-management system. For example, the system may activatevarious heat sources to respond to desired heat demands, such as arequirement for hot shower water. Additionally, the control board may beconfigured to select one of several heat sources (for example,electricity via a suitable AC outlet, a burner, or from the vehicleengine itself). While the vehicle is operating, the vehicle's engine maybe the best most efficient source of heat for the demands of the system.The burner (which may be diesel powered) provides a heat source whereelectricity is unavailable. The system may monitor a variety of sensorsfor determining the level and temperature of heating fluid (e.g. glycol)in the heating system.

[0033] Altitude Compensation Feature of System and Method Invention.

[0034] Still referring to FIGS. 5-9, the heating system of the inventionis shown for use with either low-pressure or high-pressure diesel-firedheaters (FIGS. 5-6 for low-pressure ones and FIGS. 7-9 for high-pressureones). Referring to FIG. 5, an electronic atmospheric pressure sensor isconnected to a micro-controller via an amplifier and suitable auxiliaryconditioning circuitry. The controller is programmed to control thespeed of a combustion fan (which provides a quantity of combustion air)or to control the surface/size of an air-intake opening whilemaintaining the speed of the combustion fan constant. Themicro-controller is suitably programmed automatically to: (i) increasethe speed of the combustion fan or the surface of the air-intake opening(also referred to as an orifice) upon receiving signal information fromthe altimeter/atmospheric-change sensor that the atmospheric pressure islower (higher altitude or cold weather); or (ii) decrease the speed ofthe combustion fan or the surface of the air-intake opening if thealtimeter sends signal information that atmospheric pressure is higher(lower altitude/warmer weather). In other words, based upon signalinformation from the altimeter that an incremental change in atmosphericpressure has occurred, the micro-controller is constructed automaticallyto change the speed of the combustion fan or the surface of the airintake orifice (increase for higher altitude/colder weather or decreasefor lower altitude/warmer weather).

[0035] The adjustment to the combustion air (speed of the combustion fanor surface of the air intake) is experimentally determined for eachapplication and then suitably stored in the memory of themicro-controller via suitable data-entry components such as a keypad.Using a micro-controller (and preferably a flash micro-controller) andcustomizable software for programming the micro-controller, the samehardware can be used for all the possible applications of low- or high-pressure heaters.

[0036] According to the system and method of the invention, forhigh-pressure heaters the fuel delivered to the fuel-atomizing subsystemis maintained substantially constant relative to atmospheric-pressurechanges (altitude or weather changes). To maintain the same heat output,the same system and method as described for low-pressure heaters isutilized. If the desired application calls for lower heat output inlower atmospheric pressure conditions, the system and method of theinvention is constructed to control the amount of fuel delivered usingthe same hardware as described above and shown in FIGS. 5-9 (atmosphericpressure sensor, amplifier, conditioning circuitry and micro-controller)in conjunction with a fuel metering device such as a fuel-metering pumpor a fuel-metering valve.

[0037] Automatic Air Bleeder

[0038] Referring back to FIG. 4, the automatic air bleeder of theinvention includes a suitable sensor (such as an optical or ultrasonicone) mounted adjacent a suitable air accumulator (for optical sensors,substantially transparent or clear glass, or a plastic tube aresuitable; for ultrasonic sensors, plastic or rubber tubes are suitable).Also included is an air-release solenoid and a fuel return line.

[0039] To operate the automatic air bleeder, once the air in the airaccumulator tube reaches the level of the sensor, a pulse is generatedby the conditioning circuitry and the air release solenoid will be openfor short time to release the air accumulated into the air accumulator.The duration of the pulse generated by the conditioning circuitry isproportional to the size of the air bubble detected. A return-fuel lineis mandatory for safety reasons because when the air-release solenoidopens, a small amount of fuel is released back into the fuel tank. Ifthere is no air in the fuel line, then the solenoid is closed (as it iswhen the fuel pump is deactivated/OFF).

[0040] The disclosure set forth above encompasses multiple distinctinventions with independent utility. While each of these inventions hasbeen disclosed in its preferred form, the specific embodiments thereof,as disclosed and illustrated herein, are not to be considered in alimiting sense as numerous variations are possible. The subject matterof the inventions includes all novel and non-obvious combinations andsub-combinations of the various elements, features, functions and/orproperties disclosed herein.

We claim:
 1. A heat management system connectable to a hydronic heatingsystem that includes a combustion fan and a combustion-air-intakeopening, comprising: an atmospheric-pressure sensor capable of sendingsignal information about changes in atmospheric pressure; and acontroller coupled to the sensor and programmed to control the speed ofthe combustion fan based upon signal information received from thesensor.
 2. The system of claim 1 wherein the controller is programmed tocontrol the size of the opening while maintaining the speed of thecombustion fan constant.
 3. The system of claim 1 wherein the controlleris a micro-controller.
 4. The system of claim 2 wherein the controlleris a micro-controller.
 5. The system of claim 3 wherein themicro-controller is programmed automatically to increase the speed ofthe combustion fan upon receiving signal information from the sensorthat the atmospheric pressure is lower and to decrease the speed of thecombustion fan if the sensor sends signal information that atmosphericpressure is higher.
 6. The system of claim 4 wherein themicro-controller is programmed automatically to increase the size of theopening upon receiving signal information from the atmospheric-changesensor that the atmospheric pressure is lower and to decrease the sizeof the opening if the sensor sends signal information that atmosphericpressure is higher.
 7. A heat management system connectable to ahydronic heating system that includes a combustion fan and acombustion-air-intake opening, comprising: an atmospheric-change sensorcapable of sending signal information about changes in atmosphericpressure; and a controller coupled to the sensor and programmedautomatically to change the speed of the combustion fan based uponsignal information received from the sensor that an incremental changein atmospheric pressure has occurred.
 8. The system of claim 7 whereinthe controller is programmed to change the size of the opening whilemaintaining the speed of the combustion fan constant based upon signalinformation received from the sensor that an incremental change inatmospheric pressure has occurred.
 9. A heat management systemconnectable to a hydronic heating system with control circuitry,comprising: an automatic air bleeder including a sensor mounted adjacentan air accumulator and structured to send signal information to thecontrol circuitry; and wherein the control circuitry is coupled to theair bleeder to activate it upon receiving signal information from thesensor.
 10. The system of claim 9 wherein the sensor is chosen from thegroup consisting of an optical or ultrasonic sensor.
 11. The system ofclaim 9 wherein the accumulator is chosen from the group consisting ofsubstantially transparent glass, clear glass, a plastic tube, or arubber tube.
 12. The system of claim 9 further including an air-releasesolenoid and a fuel return line.
 13. The system of claim 10 furtherincluding an air-release solenoid and a fuel return line.
 14. The systemof claim 11 further including an air-release solenoid and a fuel returnline.
 15. A heat management system connectable to a hydronic heatingsystem that includes a fuel-metering device, comprising: anatmospheric-pressure sensor capable of sending signal information aboutchanges in atmospheric pressure; and a controller coupled to the sensorand programmed to control the amount of fuel delivered to the system viathe fuel-metering device based upon signal information received from thesensor.